Diamond Buying Guide: Facts and a Step-by-Step Breakdown

The stressful process of buying diamonds...​

Buying a diamond can be an exciting process, especially when it's for a loved one in the form of an engagement ring, anniversary gift, or other surprise. 💎Diamonds have mesmerized human beings for centuries, and it’s easy to see why their eerie white glow was thought to have mystical powers suited only for the highest class individuals. Today, anyone can purchase diamonds for the right price.

However, the diamond buying process can also be extremely stressful, as buyers suddenly realize that all diamonds are not created equally. So how can you make smart decisions in your diamond buying process?

In this diamond buying guide, we will review:👇🏻

  • The ins and outs of diamonds as gemstones/minerals
  • The basics of commercial diamonds: shapes, anatomy, qualities, and more
  • How to buy diamonds online step-by-step

Diamond Buying Guide: Facts and Step-by-Step Breakdown

Diamonds: their origins and popularity

Unlike other precious stones, diamonds primarily consist of one element: carbon. In fact, they are 99.95% carbon with only 0.05% trace elements. Additionally, all of a diamond’s carbon atoms are structured in the same direction, which creates a sturdy crystal that’s difficult to break. Their chemical composition and unique structure make diamonds 58x harder than any other natural substance on earth!

Diamonds require extremely high temperatures and pressure while forming. These conditions occur about 100 miles beneath the earth’s surface, and some diamonds take millions of years to develop.

Outside of their universal appeal, many ancient cultures believed diamonds have supernatural powers.😎 Hindu culture states that diamonds were created when lightning struck rocks, and they are thought to provide mental clarity and protection from poison and enchantments. Today, diamonds are the most popular gemstone in the world!

🎯Understanding the basics of diamonds: shapes, anatomy, the 4Cs, and more

All buyers can agree that they want to get the best diamond for their budget. However, this process is a bit more nuanced than many realize. Those who favor larger diamonds soon understand that size does not equate to quality, and a larger gem may not be the brightest or most brilliant stone they can afford. Inversely, those who focus on the quality of their diamond discover that they may have to sacrifice size for a well-cut stone with high clarity and color.

Diamond buying is a complex process, and that’s why we’ve developed this diamond buying guide to introduce you to all of the properties of diamonds and how they interact to define a gem’s value.

Our recommended learning roadmap

Learning RoadmapIt’s crucial to learn about diamond shapes, anatomy, the 4Cs, and grading reports to have a well-rounded understanding before buying. Studying the properties of diamonds and how they intertwine is paramount to making smart purchasing decisions and finding a diamond that matches your ideal size, color, and sparkle.

Here is a brief step-by-step breakdown of the important characteristics to consider when buying a diamond:

  • Pick the right shape: This is the first characteristic you will notice about a diamond. Whether you prefer round, emerald, or heart-shaped stones, a diamond’s shape will affect how light travels through it and how it will sparkle. The shape can also affect how often your diamond will snag on clothes, hair, and other materials, so choose wisely to avoid damaging your piece.
  • Learn about anatomy: A diamond is the sum of its parts, so learning more about the table, girdle, and other parts of a diamond can help you discern what shapes or styles you like best. Understanding the pieces that make up a diamond is also the first step to grasping the 4Cs, as different measurements can affect a stone’s shine.
  • Memorize the 4Cs: The 4Cs are a great tool for figuring out whether a diamond is high-quality or not. The 4Cs can tell you about a diamond’s scintillation, weight, clarity, and so much more. Use these tools to do your research and compare diamonds to find the right stone for you.
  • Read the diamond grading report: The three factors above are encapsulated in the diamond report, which lists the details of your stone from shape to grade. Learning how to read a diamond report means you’ll have all of the important information at your disposal for every diamond you evaluate, and you can make an informed buying decision.🌟

Choosing a diamond shape

There is a plethora of diamond shapes to choose from, each providing its own unique shine:


Diamond Shape: RoundThe most popular shape, round diamonds often have a “brilliant” cut to bring out the deepest colors of their fire. Round diamonds are also great for individuals who tend to snag their jewelry due to their lack of corners. They look great on both long and short fingers, so they’re ideal as an engagement stone for any future bride!👰🏻


Diamond Shape: Square (Princess Cut)The dynamic look of a square diamond fits any setting. The most popular style is the princess cut, followed by the Quadrillion cut. Square diamonds do require sturdier settings to protect their corners from damage. Also, make sure all sides of the stone you choose are parallel and look for length-to-width ratios of about 1.0 to 1.05 for an ideal shape.


Diamond Shape: Rectangle (Cushion Cut)Rectangular diamonds come in a variety of cuts, including cushion and baguette. The larger surface area of rectangular stones make bigger inclusions rather visible, so choose a quality gem to avoid this. As with square diamonds, ensure your rectangular diamond has parallel sides and even corners.


Oval Diamond ShapeSimilar to the brilliance of the round cut, the oval diamond is perfect for long, slender fingers. This style dates back to 1304, but it has become increasingly popular over the last decade. A famous example of an oval diamond is the Koh-i-Noor, a 105.6-carat oval diamond that is part of the British Crown Jewels!


Marquise Shape DiamondAnother shape for long or delicate fingers, the marquise diamond maximizes carat weight and makes a smaller stone appear larger. It was inspired by the mistress of King Louis XV and resembled the shape of her lips. With a marquise diamond, prioritize symmetry, as a slight imbalance can make the whole gem appear uneven.


Diamond Shape: PearPear stones are the perfect hybrid of the round and marquise diamonds. They make larger fingers appear smaller if the pointed end faces upward, and they’ve gained favor as a center and side stone in the last few years. Similar to the marquise, pear diamonds require symmetry to look sharp.


Octagonal Diamond: Radiant CutOctagonal diamonds are notorious for the emerald shape, which has become rather trendy. The mirror-like surface of these stones come from their step-cut facets and large table. Much like rectangular diamonds, clarity is key to avoid any visible inclusions. Other popular octagonal diamonds adopt radiant cuts or Asscher cuts.


Heart Shape DiamondA unique shape, heart diamonds are rare to find. ❤️This romantic design relies on symmetry and a sharp point to provide a feminine touch to diamonds.


Triangle DiamondTypically cut in brilliant style, triangular diamonds are usually side stones. As with other shapes, clarity is important to hide visible inclusions.

The anatomy of diamonds

Diamond anatomy

Gem cutters have the tough job of ensuring a diamond’s facets are cut not only precisely and within desired ratios, but also in a way that does not negatively affect a stone’s sparkle and reflective properties.

This table breaks down each part of a diamond’s anatomy:

Diamond Anatomy: Different Parts of a Diamond

Diamond PartDescription
TableThe top, horizontal side of a diamond, which is also its largest facet
CrownThe top portion of a diamond, which extends from the table to the girdle
PavillionThe bottom section of a diamond, extending from the bottom of the girdle to the culet
GirdleThe edge where the crown and pavilion meet; it defines the perimeter of the diamond
CuletThe facet at the end of a diamond that protects against chipping
DepthA diamond’s total height from the top of the table to the bottom of the culet
DiameterA diamond’s total width, measures from one end of the girdle to the other
Diamond fluorescence

Fluorescence is another factor in a diamond’s anatomy. When certain diamonds are exposed to a UV light source, they glow an eerie blue, yellow, or orange. Only 25–30% of diamonds fluoresce, and prices for diamonds that do and do not fluoresce are typically about the same. However, diamonds with D-H color may see a minute price reduction compared to I-M color stones, which may see a slight price increase.

The 4Cs of diamonds

📣The 4Cs of diamonds are color, cut, clarity, and carat. We’ll explain each feature and how it’s measured by the Gemological Institute of America (GIA), as the American Gem Society (AGS) uses its own rating system. Then, the diamond buying guide will teach you how to track these qualities when purchasing diamonds.


A diamond’s cut includes grading the facets and how well they interact with light. There are seven components to diamond cut grading. The first three perceptive factors, fire, brightness, and scintillation, measure a diamond’s face-up appearance. The last four are technical factors—proportions, culet size and girdle thickness, polish, and symmetry—that designate a diamond’s overall design and craftsmanship. The technical factors impact the three perfective qualities, which results in a rating on a scale from “Excellent” to “Poor”.⭐️

The Fire and Scintillation of a Faceted Diamond


This criterion rates how colorless a diamond may be. The GIA grades diamonds on a scale of D to Z, with D being colorless and increasing to Z. The further down the scale you go, the more yellow your diamond will appear. However, color differences among two stones that are one grade off can be difficult to notice without training!


Diamonds are a byproduct of natural occurrences, so sometimes they have imperfections. Clarity measures these imperfections, known as “inclusions” inside the diamond and “blemishes” outside the stone. Diamond clarity involves understanding the amount, size, relief, nature, and position of these imperfections and how they affect the overall look of a diamond.

Diamond clarity is rated as follows:

Clarity Scale GradeDefinition
IFInternally Flawless
VVS1Very Very Slightly Included (1)
VVS2Very Very Slightly Included (2)
VS1Very Slightly Included (1)
VS2Very Slightly Included (2)
SI1Slightly Included (1)
SI2Slightly Included (2)
I1Included (1)
I2Included (2)
I3Included (3)


Carat is the measure of how much a diamond weighs, and one carat is equivalent to 200 milligrams. Jewelers measure diamonds to the hundredths place, so a gem maybe 1.02 carats, 3.45 carats, etc.

As a general rule, larger diamonds typically garner higher prices. ⚠️However, two stones of almost equal size may have very different price tags if one has an excellent cut and very few inclusions when compared to the other.

Bonus info: Rough vs. polished diamonds

Bonus InfoMost of us recognize the cut diamonds sold in jewelry stores, but you can actually purchase rough diamonds too. Polished diamonds are graded using the 4Cs and have faceted cuts that bring out the gems’ inner “fire”.

However, a rough diamond is a gemstone in its natural state before anyone cuts it. They’re typically less expensive than polished stones, meaning you can buy a larger diamond for a portion of the price.

These stones appear murky or quartz-like. Just like polished stones, they can have inclusions or discolorations, and they are more likely to have these problems than polished stones as they have not been refined by a professional.

The diamond grading report

You can find a full explanation of the 4Cs and anatomy of any diamond in the gemstone’s grading report. Understanding how to read this document is paramount to discerning the value and quality of your selected gem. You can refer to the picture of the GIA grading report below when reading about each section of the document:


At the top of each report, you can locate the name and emblem of the diamond authority who graded the gemstone. The major names you may find are GIA, AGS, IGI, HRD, and EGL, but there are also lesser-known organizations that grade diamonds as well

Report number

This section shows you the report number, the date the report was issued, and the diamond’s shape, cut, and dimensions.

The 4Cs and other grading criteria

  • “Grading Results” section: details the stone’s carat weight, followed by its color, clarity, and cut grades. The scales for each grade are also listed on the right side of the document.
  • “Additional Grading Information” section: provides details about a few other crucial factors, such as polish, symmetry, and fluorescence. Finally, the “Comments” area covers anything that hasn’t already been said: laser inscriptions, specific inclusions, and other identifying information.

Diagrams and visual aids

  • Proportions diagram: It gives you a great idea of your gem’s physical attributes for understanding table percentage, depth, percentage, etc.
  • Clarity diagram: It displays any inclusions or blemishes, and the diagram’s key is ideal for figuring out what kind of imperfections your stone has.

Marks of authenticity

Finally, the bottom right of the diamond grading report contains several security measures that verify the document’s validity. These measures may include a watermark, hologram, embossed stamp, security screens, a two-dimensional barcode, and/or sheet numbering.

A GIA Diamond Report

Image: GIA

A step-by-step guide to buying a diamond online

💭Questions before you buy

Buying loose diamonds online is easier than ever, with online retailers who walk you through each step. But, before consulting our diamond buying guide, ask yourself:

Do I want a loose or set diamond?

Are you buying a diamond that your retailer will fit into a jewelry piece? Or, would you prefer to purchase a loose diamond for your personal collection? If you’re looking to create a jewelry piece with your retailer, consider the setting you may want for your diamond, such as a pendant or ring.

Should I buy from a local or online retailer?

The best place to buy diamonds maybe with a jeweler you feel comfortable working with. You can purchase from online retailers, but some people prefer speaking to a professional in person. Just make sure your jeweler has the right accreditations from nationally recognized programs, such as the GIA Gemologist (GG) or Applied Jewelry Professional (AJP) programs. You can also search “jewelry stores that buy diamonds near me” to find a list of potential jewelers!

Buy Diamond Online vs. in a Local Store

Do I want a natural diamond or a lab-grown diamond?

Are you looking for a diamond naturally created within the earth’s crust or one made in a lab by skilled scientists? Nowadays, lab-grown diamonds are just as stunning as natural ones for a fraction of the price! If you want to expand your budget’s potential, consider a moissanite diamond or equivalent that can help you buy more for less.

What’s my budget?

Figure out what you’re willing to spend! If you have your heart set on a 1-carat diamond, shop around to find the average price for the qualities you’re looking for. Once you have a price range, set your budget, and adjust accordingly.

Purchasing a loose diamond: a step-by-step diamond buying guide

There are plenty of retailers who can help you buy a loose diamond. James Allen has a carefully selected inventory of loose diamonds for you to purchase, and we’ll walk you through their online platform below.

Visit the “Loose Diamonds” page

To start, visit the loose diamonds page. For this tutorial, we will look at round diamonds. The home page lets you narrow your search by the 4Cs, so you can select your ideal cut, clarity, color, carat, and price range.

Selecting Desired 4Cs Gradings of the Diamonds

Once you’ve added your criteria, you’ll be able to view all of the diamonds that fit those specifics.

James Allen: Diamond Search Results

Select a diamond and review its characteristics

Once you find a diamond you like, click on the picture and read more about it. James Allen also offers a 360° panoramic display of your diamond: drag your mouse from left to right over the image and it will automatically rotate so you can inspect each facet. You can even zoom in on the diamond’s picture to get a better look at its inclusions and cut. This allows you to choose a diamond that is “eye-clean” or that looks free of flaws when viewing it with the naked eye.

Review the characteristics of a chosen diamond

Review the characteristics of a chosen diamond

Below the diamond’s photo is more detail regarding the stone’s qualities, including fluorescence, symmetry, and ratios. The “Certificate” detail allows you to see who has verified the quality of this gem. ✅We recommend sticking with GIA and AGS certified diamonds, as their gemologists follow strict quality guidelines.

More Detail Regarding the Chosen Diamond's Qualities

If you’re still unsure whether this diamond is right for you, you can opt for a “Real-Time Diamond Inspection”, which is located above the diamond’s details. James Allen keeps professionals on hand to answer questions during your purchase.

Initiate a Real-Time Diamond Inspection on James Allen

Initiate a real-time diamond inspection

Compare prices

Once you’ve selected your diamond, make sure you do some research with other sellers to ensure you’re getting a fair deal. Blue Nile also sells loose gemstones, so you can compare the stone you’ve chosen with one of comparable quality on their website. Similar to James Allen, you can select specific characteristics to narrow your search.

Search Diamonds on Blue Nile With Specific Characteristics (4cs, Price Range and More)

For instance, this stone is fairly close to the one we’ve chosen, and the price is a bit higher. However, given the slight differences between the two stones—such as the Ideal cut rating for the Blue Nile diamond—we can see we are getting a fair price with James Allen.

A Blue Nile Diamond With Similar Characteristics of the One from James Allen

Here is a list of some well known online retailers with gorgeous diamonds for sale where you can compare prices:

Add your diamond to your cart

Now that you’ve selected your diamond and compared prices, you can complete your purchase. Click “Select this diamond” to add it to your cart.

Add the Desired James Allen Diamond to Cart

You can now go enter your information to securely checkout with your item. James Allen also offers FAQs alongside the platform where you’re entering your information in case you have any questions along the way.

James Allen FAQs During Checkout

James Allen FAQs during checkout

After you’ve completed your purchase, your final step is to wait for your beautiful loose diamond!

Consider a setting

💡Before you can add the diamond to your cart, James Allen gives you the option of setting the stone or purchasing a loose gem. If you’ve thought about setting your new diamond in a ring or pendant, consider clicking “add a setting”.

Opt for a Setting or Pendant for the Diamond

Next, carefully select your setting. James Allen gives plenty of customization options with any metal you’d like: platinum or yellow, white, or rose gold in 14K and 18K selections.

Choose a Setting for the Diamond

Choose a Setting for the Diamond

Finally, after you’re chosen a setting, add it to your cart and complete checkout as normal.

Research the details

Finally, it’s important to research the purchase details of your respected retailer. Here are some transaction requirements to watch for:


Most quality diamond retailers offer a warranty for their products. This could be a limited warranty or a lifetime warranty that protects your diamond forever. For instance, James Allen offers a lifetime warranty that covers free rhodium plating, cleaning services, re-polishing, and prong tightening as well as evaluation services.

James Allen Offers Lifetime Warranty

Learn more about James Allen's lifetime warranty

Customer Service

You want to find a jeweler who will be there to answer your questions and assist with returns. For many, this means finding a local jeweler they can visit whenever there is a problem. Others prefer an online retailer with a dedicated customer service phone line, online chat service, or email. Whatever jeweler you choose, make sure they provide quality aid for damage and repair. Most jewelers even offer a full refund for items returned within 30 days of purchase!

Financing Options

If you’re not buying your diamond outright, research the financing options available. Many retailers allow you to schedule a payment plan so that you can pay a little each month with interest. 💻 It’s important to do your own calculations and make sure the payment plan and interest percentage offered are something you can afford. James Allen even offers a payment plan with deferred interest if the balance is paid off in six months!

Affordable Payment Plan Offered by James Allen

Payment Method

Most jewelers accept cash and major credit cards: MasterCard, Visa, American Express, and Discover. However, some also accept checks and wire transfers, so ask your jeweler before purchasing to ensure there’s an accepted method that suits your needs.


Be sure to find a jeweler that offers secure shipping: you don’t want to lose your item before it even makes it to your home! Most shipping takes 1–2 weeks depending on the jeweler’s inspection process. For example, James Allen takes 1–4 days after purchase to have all loose diamonds closely inspected by gemologists before shipping.💡


Consider insuring your new diamond. While not necessarily offered through retailers, many can offer insurance appraisals with your purchase. Insuring your diamond protects your investment and provides additional security over time.

Do your research before buying loose diamonds

Buying a loose diamond is simpler than ever, and purchasing diamond rings and wedding bands is now a less painful process.

Today, you can do the research yourself and understand a diamond’s quality without feeling as though you’re being sold to.💎 In this diamond buying guide, several suggestions were given regarding where to buy diamonds, but that decision comes down to what you are most comfortable with.

While the research may be available to all, many people may still prefer to consult an expert jeweler while buying their diamond, and this is perfectly alright! It’s understandable to want a professional to walk you through the differences between diamonds and why they matter. Diamond buying is a personal process, and however you want to handle the ins and outs of purchasing gemstones is up to you.

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